Reconciliation Between the Statutory U.S. Income Tax Rate and the Bancorp's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Statutory Federal Tax Rate [Abstract]
Statutory tax rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	1.70%	1.40%	1.20%
Tax-exempt income	1.70%	1.40%	1.10%
Credits	7.50%	8.10%	6.00%
Unrealized stock-based compensation benefits			0.30%
Other, net	0.30%		0.30%
Effective tax rate	27.80%	26.90%	29.70%